My 2014 Toyota Corolla has developed a cracked moonroof. Has anyone the same problem ?
It’s made of glass. Glass can have flaws in it that makes it subject to cracking under the right conditions. Or it could have gotten hit by a rock kicked up by a semi at some point, and only now is the crack large enough for you to notice it.
Have it fixed and drive on - but keep your receipt in case it turns out there is an issue with your specific car (a brief Google search did not show any evidence of that yet) and you might get reimbursed.